Several years ago Dan Wolf, a San Francisco-based musician, writer, rapper and performer, discovered that he was the heir to a Vaudeville tune called “Tuedelband,” the signature song of the city of Hamburg. The song is so famous that it starts off the classic 1981 German film “Das Boot,” and is still sung at soccer games. A documentary called “The Return of the Tuedelband” was even made in Germany about Dan Wolf’s return to Germany to learn more about his family, and its cultural legacy.